In many engineering applications, it is desirable to employ porous carbon in the form of solid monoliths (discs, plates, shaped conformal elements, hemispherical components, carbon honeycombs, etc.) rather than granular material. The advantages of the monolithic configurations over granular carbon are listed below.                higher packing density        higher mechanical strength        lower pressure drop for a gas or liquid flow through channels (e.g., in a honeycomb element) versus through a packed bed of granular material        higher thermal conductivity        higher electric conductivity        lower propensity to generate fine particles as a result of attrition        ease of carbon sorbent regeneration, e.g., by resistive heating (applying voltage to the ends of carbon monolith)        
Disadvantages of carbon monoliths with respect to granular carbon include: (1) a more complex carbon manufacturing process, often associated with a higher cost (e.g., the need to predict monolith shrinkage during carbonization and activation, the need to control monolith fracturing and warpage); and (2) more difficult control over the development of carbon porosity in the process of carbon activation.
The advantages of monolithic porous carbon over non-porous carbon, such as graphite or carbon fibers, are the better developed internal surface area and porosity, sorptive properties, and lower density. The disadvantages are the lower mechanical strength and the generally lower electrical and thermal conductivity. The latter two properties, however, may actually be desirable, depending on application, e.g., where materials with insulating rather than conducting properties are needed.
Examples of applications in which the use of monolithic porous carbon is, or may be, desirable are:                1. electrodes for electrochemical ultracapacitors, e.g., for use in hybrid vehicles, spacecraft and military systems (e.g., submarines, electromagnetic rail guns), and consumer electronics (cellular phones, etc.);        2. radiation shielding for spacecraft and high-altitude flights;        3. high-strength structural or surface components of spacecraft and military vehicles;        4. porous carbon plates, or differently shaped elements, for ballistic, thermal or micrometeorite orbital debris (MMOD) protection, e.g., for soldier armor plates (Small Arms Protective Inserts, or SAPIs), military vehicle armor, helmets, spacecraft outer-body plates or shields for ablative and MMOD protection;        5. gas-storage sorbents, e.g., for hydrogen storage for fuel cells, natural-gas or methane storage for gas-powered vehicles, safe storage and transportation of toxic gases, such as arsine, silane, phosphine, and boron trifluoride, and carbon sorbents for Radon testing;        6. carbon sorbents for the capture and containment of radioactive gases accidentally released at nuclear power plants;        7. supports for liquid or solid sorbents or catalysts, e.g., for liquid amines used to remove carbon dioxide from combustion flue gas, or from ambient air in air-revitalization systems (spacecraft, submarines, etc.).        
It should be appreciated that, at least in some applications, combining two or more functions of monolithic carbon may be highly desirable, resulting in reduced weight, increased performance, and better overall efficiency of resource utilization. For example, large-size prismatic ultracapacitors with porous carbon monolith electrodes could be used for individual soldier's energy storage, in lieu or in addition to batteries, while at the same time providing ballistic protection in the form of SAPIs. A scaled-up implementation of the same idea could be used in armored vehicles' protective shields. Another example of dual-use monolithic carbon is carbon-filled conformal hydrogen storage tanks on board spacecraft that are arranged to form a shelter protecting astronauts from cosmic radiation. Yet another example of a multifunctional carbon implementation is the combination of ultracapacitor electrodes with radiation shielding, and optionally also with MMOD protection and/or ablative shielding. It will be appreciated by those skilled in the art that the above examples are provided only for the sake of illustration, and that many more multifunctional uses of carbon are possible